Manufacture of motor fuel



ug. 14, 1945. H. R. wARRlcK MANUFACTURE OF MOTOR FUEL v Filed Dec. 22,1943 Patented Aug. 14, 1945 MANUFACTURE F MOTOR FUEL Balsted RogersWarrick, Teaneck, N. J., assignor to The Texas Company, New York, N. Y.,a corporation of Delaware Application December 22, 1943, Serial No.515,215

6 Claims. (OLMO-683.4)

This invention relates -to the manufacture of motor fuel andparticularly to its manufacture from normally gaseous saturatedhydrocarbons.

'Ihe present application is a continuation-inpart of my applicationSerial No. 326,593 filed March 29, 1940.

The invention broadly contemplates conversion of normally gaseoussaturated hydrocarbons such as ethane and propane to motor fuelhydrocarbons of high anti-knock value by a process in- 10 In order todescribe the invention more fully, volving thermal conversion of thesaturated hyreference' will now be made to the accompanying drocarbonsto form a synthetic hydrocarbon mixdrawingillustrating one method of nowsuitable ture containing unsaturated hydrocarbons infor practicing theprocess 01' the invention. cluding ethylene and higher molecular weightAs indicated in the drawing, a normally gaseoleflns. The syntheticmixture is subjected to ous hydrocarbon charge comprising ethane,propolymerization such that the higher molecular pane, butene o1 amixture Containing any of these weight olens are-converted to polymergasoline hydrocarbons in substantial amount is conducted leaving ahydrocarbon fraction consisting essenthrough a pipe l. The Charge iSpassed through tially of ethylene. The ethylene is then suba heater 2wherein it is subleoted to thermal Conjected to alkylatlon withlsobutane. 20 version by heating to a temperaturein the range Morespecifically, the invention involves ther- 0f around 1000 t0 1400 F- andunder ,a pressure mal conversion of ethane, propane, normal bu- Whichmuy ronge from atmospheric to 500 ibstane or a hydrocarbon mixturecontaining these per square inch gauge or higher. Thetemperahydrocarbons et elevated temperature to form a ture end pressureconditions to be used will desynthetic mixture containing ethylene andhigher pel-'id on the nature 0f the Charge and also 0X1 molecular weightolen hydrocarbons as well as the relative amounts of liquidhydrocarbons. converted hydrocarbons boilingwlthin the range propyleneand ethylene desired during the pyrolysultable for motor fuel. Thismixture is treated sis'step. As e rule, extremely higher pressure fatoremove the normally liquid polymer gasoline Vors liquid productformation at the expense 0f hydrocarbons and to segregate a normallygasepropylene and ethylene. On the other hand, ous hydrocarbon fractioncontaining ethylene and lower pressure favors the production of normallyhigher molecular weight olens such as propylene gaseous olens. The timeof exposure to the eleand butylene. This segregated fraction is sub-Voted temperature may range from about 1 to jected to catalyticpolymerization so as to con- 100 seconds for the production of ethyleneor for vert substantially all of the propylene and butylmaximum oleiinproduction. ene to polymer gasoline hydrocarbons. The un- As a result ofthe thermal conversion treatconverted material comprising ethylenesubment, the Conversion miXture may Contain stantially free frompropylene and butylene is around 10% t0 25% by volume of ethylene. Inthen subjected to alkylation with isobutane in addition, this mixturewill contain hydrogen, the presence of a suitable alkylatlon catalyst.methane,- prop-ne, propyiene, normal and iso bu- The alkylation isadvantageously effected by tanes and butylenes, as well as highermolecular contact with an active metallic halide catalyst at Weighthydrocarbons boiling up to about 500 F. relatively low temperatures aswill be described This synthetic mixture is passed from the heater inmore detail, 2 to an absorption tower 3 whereinit is sub- An object ofthe invention is to obtain the iected to scrubbing with a stream ofpolymer maximum conversion of ethane and propane as gasolinehydl'ooarbons drawn of! froma subsewell as normal butane into valuablegasoline hyqllent point in the process and Which scrubbing drocarbons 0fhigh antiknock value, This inmedium is introduced to the absorptiontower vclves the vformation of a substantial amount of through a Pipe 4-ethylene and therefore a further object of the The liquid fractionCollecting in the bottom of invention involves the conversion of thisethylene the absorption tower 3 is withdrawn throush a into highantikncck hydrocarbons suitable for pipe 5 and Will comprise polymergasoline hydroaviation motor fuel, carbons including some C4hydrocarbons. It is It has been known heretofore to subjecthydrodesirable to operate the absorption tower so that carbons such aspropane to thermal conversion 55. the unabsorbed hydrocarbons will notinclude Cs to produce olefin hydrocarbons and polymer gasoline. Suchconversion has involved the production of large amounts of ethylenewhich has been dimcult toV dispose of in an economic manner. It has nowbeen found possible to effectively dispose of this 'ethylene byalkylation with isobutane in the presence of a metallic halide catalystWhere the conditions of alkylation are carefully controlled as will -beset forth later.

hydrocarbons, at least to any substantial extent.. This mixturecontaining absorbed hydrocarbons,l mainly Cs and heavier, is passed to astabilizer 6 wherein it is stabilized by vaporizing the desired amountof low boiling hydrocarbons. The stabilized polymer gasoline is drawnoil' from the system through a pipe l and will comprise gasoline havingan antiknock value of around 80 12085 (CFRM).

The low boiling hydrocarbons vaporized in the stabilizer t are removedthrough a pipe t and maybe recycled all or in part through a branch pipe2 to the heater 2. If desired, these vaporized hydrocarbons may bepassed all or in part through a. pipe It communicating with a pipe il,leading to a catalytic polymerization unit i 2 to Awhich reference willbe made.

The normally gaseous hydrocarbons accumulating in the upper portionofthe absorber 3 and which comprise ethylene, some propylene andbutylene, as well as more volatile materials, are passed to a.fractionator I3. The purpose of the i'ractionator I3v is to removegaseous constituents such as hydrogen and methane which are drawn oilthrough a pipe I4 and which may be disposed of as refinery fuel or insome'othei` manner as may be desired. The fractionator I3 is operatedunder conditions of temperature and pressure necessary in order toremove the hydrogen and methane from the ethylene and other hydrocarbonconstituents present in the mixture entering the fractionator I3. y

The ethylene and other hydrocarbons, including propylene and butyieneare drawn off through a pipe I5, communicating with the previouslymentionelz pipe I I leading to the catalytic polymer unit In thecatalytic polymer unit the hydrocarbons v are subjected to contact 'witha polymerization from the polymer unit will contain propylene andbutylene in amount substantially less than 20%, and preferably not inexcess of about 10%. by weight of the ethylene present. For example, thepropylene and butylene content will be about 1% to about 5% of theethylene, and may be as high as about 5 to 10%.

One purpose of the polymerization step is to Yreduce the quantity ofolens of higher molecular weight than ethylene so that the ethylene canbe subjected to alkylation in an eil'ective manner.

Thus, it has been found that the presence of excess propylene andbutyiene causes considerable diiculty in the subsequent alkylation ofethylene with' aluminum chloride as an alkylation catalyst since thesehigher molecular weight olefins cause rapid deterioration of thecatalyst.

In the alkylation of ethylene with isobutane so las to produce analkylate having a large content of 2,3 dimethylbutane, the presence ofmore than 10% of these higher molecular weight olens in the ethylenefeed to the alkylation reaction is undesirable. The presence of morethan 10% of4 these higher molecular weight olens materially reduces theyield of 2,3 dimethylbutane and results in an alkylate of lower octanevalue. 'Ihe amount of ethylene reacted is reduced, and, in

addition, catalyst consumption is materially increased by thepresence ofpropylene and higher olens.

assanv While' the total absence of propylene and higher olens favorsrealizing the maximum yield of 2,3 dimethylbutane, nevertheless it isdesirable to retain in the ethylene feed to the alkylation reaction asmall amount of the higher olens, namely about l to 10% by weight of theethylene. The presence of this small amount of higher oleiiu iseffective in preventing reduction in the fluidity oi the complexcatalyst during continued use in continuous operations.

The hydrocarbons are passed from the catalytic polymer unit I2 through apipe I5 leading to a fractionator I'I. The fractionator il is operatedunder conditions of 'temperature and pressure such that the liquidhydrocarbons are condensed andremoved as a polymer gasoline from thebottom of the fractionator Il through a pipe This polymer gasoline maycontain small amounts of normally gaseous hydrocarbons such as propane,for example. Therefore it is advantageously passed to the stabilizer 6previously referred to wherein it is commingled with the polymergasoline formed directly in the heater 2. If desired, 'a portion ofitmay be recycled through a pipe I9 Acommunicating with the` pipe tleading y 'passed through a pipe 20 to an alkylation unit 2| wherein theethylene is subjected to `alkylation with isobutane by contact with anactive alkylation catalyst. The alkylated hydrocarbons are passedthrough a pipe 22 to a depropanizer 23 wherein normally gaseousconstituents comprising mainly ethane and propane are separated from thehigher boiling hydrocarbons. The depropanizer may comprise afractionating tower or an absorption tower. Where it is operated as anabsorption tower, the absorption medium may comprise straight-rungasoline with which it may be desired to blend the debutanized alkylatedhydrocarbons. The absorption medium may also comprise a portion of thedebutanized alkylate itself as will be explained later.

'I'he ethane and propane separated from the alkylate in the depropanizermay be discharged all or in part through a pipe 24. However, it isadvantageous to recycle these hydrocarbons to the heater 2. carbons areforced by a compressor 25 through a pipe 26 communicating with theheater inlet or with an intermediate point in the heating coil asindicated.

To eil'ect lconversion of ethane to ethylene, it is preferable to employa high temperature, a. low pressure, and ashort time of .exposure to theelevated temperature. For example, such conversion may be effected at altemperature of around 1300 to 1400 F. under a pressure of around 1atmosphere and with a time of exposure of around 1 to 10 seconds. It isdesirable, therefore, to pass the recycledethane through that portion ofthe heating coil wherein approximately the foregoing conditions willprevail. If desired, a separate heater may be employed for thefurtherconversion of these recycled hydrocarbons.

Referring again to the depropanizer 23, thc alkylated hydrocarbonmixture from which the ethane and propane have been removed is drawn Insuch case, the recycled hydroassanv off through a pipe 21 leading to afractionatox 2l wherein the aikylated mixture is debutanized to removeisobutane which is recycled through a pipe 2l to the alkylation unit 2|along with such additional isobutane as may be required for thereaction.

Debutanized alkylate is drawn oi! through a pipe Il and comprisesgasoline having an antilmock value of 90 or-above and suitable foraviation fuel. As already indicated, a portion of this may be returnedthrough a pipe 8| to the depropanizer 2l to serve as an absorptionmedium.

The alkylation of ethylene with isobutane is advantageously effected ina manner similar to that described in copending application Serial No.327,575. A s there described, the catalyst comprises a metallic halidesuch as aluminum chloride or aluminum bromide dispersed in a fluid bodyof preformed metallic halide-hydrocarbon complex. Thus, the reactionvessel is maintained substantially filled with a body of the fluidcornplex in which is suspended solid pulverulent aluminum chloride. Themixture is subjected to continuousagitation while the ethylene feed iscontinuously passed through the agitated mass together with an excess ofisobutane, employing a pressure in the reaction sone of around 125 to250 pounds per square inch gauge.

It is desirable to maintain the isobutane in substantial molecularexcess over the ethylene undergoing treatment For example, the ethyleneand isobutane are passed through the catalyst mass in the proportion ofabout 1 part of ethylene to from 3 to 5 parts of isobutane, althougheven higher proportions of isobutane may be used, as for example 20parts per part of ethylene. A reaction temperature of around 100 -to 130F. is maintained.

, The preformed complex may comprise complex metallic halide-hydrocarboncompounds such as produced in a conventional aikylation reaction whereina catalyst such as aluminum chloride has been employed with theresultant production of Y complex compounds. The complex material may besuch as produced in the isomerization of normal parafiin hydrocarbonsduring contact with anhydrous metallic halides.

A suitable complex material may also be prepared directly by reactingaluminum chloride or other active metallic halide with paraliin orolefin hydrocarbms and particularly with olefin hydrocarbins having from3 to 4 carbon atoms per molecule. It may also be prepared by reactingthe metallic halide with alkyl halide such as propyl and butylchlorides.

In usuing the alklation catalyst, a small amount of hydrogen chloride orother hydrogen halide may be introduced along with the feed hydrocarbonsin order to promote the reaction.

While specific temperatures and pressures as -acid 0f about 84%A H2804.

acid of about 80 to 90% H2804, and preferably The absorption with suchacid may be carried out at a temperature of about 70 to 125 F. so that aresidual ethylene fraction is obtained which contains from about 1 to10% by weight of higher oleilns.

ethylene, higher molecular weight olens and I some normally gaseoussaturated hydrocarbons, passinga stream of said mixture through areaction zone wherein higher molecular weight oleiins than ethylene aresubstantially entirely converfed to polymer gasoline, removng thepolymer gasoline hydrocarbons thereby leaving a residual ethylenefraction containing some normally gaseous saturated hydrocarbons andfrom about 1 to 5% of higher molecular weight oleflns by weight of theethylene, passing a stream of said residual ethylene fraction through analkylation reaction zone containing a fluid alkylation catalystcomprising aluminum halide-hydrocarbon complex maintained underalkylating conditions at a temperature in the range of 100 to 130 F.,passing isobutane to said alkylation reaction zone in the proportion offrom 3 to 5 parts isobutane to about 1 part ethylene, effecting reactionbetween isobutane and ethylene in said alkylation zone in the presenceof a small amount of hydrogen halide to form saturated hydrocarbons ofhigh antiknock value, withdrawing the resulting alkylated hydrocarbonsand unreacted normally 1'ecul'arweight oleilns to normally liquidproducts well as other conditions of operation have; been f describedabove for each step in the process, it

is, of course, contemplated that the conditions of operation may varysomewhat from these as de-- sired without departingfrom th scope of theinvention.

While removal oi' the excess propylene'fadf- Vwithoutsubstantialconversion of ethylene, re moving-said normally liquid products therebyleavin'ga residual ethylene fraction containing son'ueJnormally gaseoussaturated hydrocarbons ,and from about 1 to 5% of higher molecularweight oleilns by weight of the ethylene, passing a stream of saidresidual ethylene fraction through an alkylation reaction zonecontaining a fluid alkylation catalyst comprising aluminumhalide-hydrocarbon complex maintained under alkylating conditions at atemperature in the range of .to 130 F., passing isobutane to saidalkylation reaction zone in the proportion of from 3 to 20 partsisobutane to about 1 part ethylene, effecting reaction between isobutaneand ethylene in said alkylation zone in the presence of a small amountof hydrogen halide to form saturated hydrocarbons of high antiknockvalue, withdrawing the resulting alkylated hydrocarbons and unreactednormally gaseous saturated hydrocarbons, and returning said normallygaseous saturated hydrocarbons to the thermal conversion reaction.

4. A continuous process for manufacturing motor fuel hydrocarbons fromnormally gaseous saturated hydrocarbons which comprises subjecting thesaturated hydrocarbons to conversion to produce a synthetic hydrocarbonmixture containing ethylene, higher molecular weight oleflns and somenormally gaseous saturated hydrocarbons, passing a stream of saidmixture through a reaction zone wherein higher molecular weight oleflnsthan ethylene are substantially converted to polymer gasoline withoutsubstantial conversion of ethylene, removing the polymer gasolinehydrocarbons thereby leaving a residual ethylene fraction containingsome normally gaseous saturated hydrocarbons and from about 1 to 10% ofhigher molecular weight olens by weight of the ethylene, passing astream of said residual ethylene fraction through an alkylation reactionzone containing a fluid alkylation catalyst comprising aluminumhalide-hydrocarbon complex maintained under alkylating conditions at atemperature in the' range of 100 to 130 F., passing isobutane to saidalkylation reaction zone in an amount sufllcient to maintain asubstantial molecular excess of isobutane over ethylene undergoingtreatment therein, effecting reaction between isobutane and ethylene insaid alkylation zonein the presence of a small amount of hydrogen halideto form saturated hydrocarbons of high antiknock value, withdrawing theresulting alkylated hydrocarbons and unreacted normally gaseoussaturated hydrocarbons, and returning said normally gaseous saturatedhydrocarbonsto the thermal conversion reaction. v

from about 1 lto 10% of higher molecular weight olens by weight of theethylene, passing a stream of said residual ethylene fraction through analkylation reaction zone containing a fluid alkylation catalystcomprising aluminum halidehydrocarbon complex maintained underalkylating conditions at a temperature in the range of 100 to 130 F.,passing isobutane,.to said alkylation reaction zone ln an amountsuflicient to maintain aisubstantial molecular excess of isobutane overthe ethylene undergoing treatment therein, effecting reaction betweenisobutane and ethylene ln said alkylation zone in thepresence of a smallamount of hydrogen halide to form saturated hydrocarbons of highantiknock value, withdrawing the resulting alkylated hydrocarbons andunreacted normally gaseous saturated hydrocarbons, and returning saidnormally gaseous saturated hydrocarbons to the thermal conversionreaction.

6. A continuous process for manufacturingmotor fuel hydrocarbons fromnormallygaseous saturated hydrocarbons which comprises subjecting thesaturated hydrocarbons to conversion to produce a synthetic hydrocarbonmixture containing ethylene, higher molecular weight olens and somenormally gaseous saturated hydrocarbons, passing astream of said mixturetoa treating zone, effecting therein conversion of higher molecularweight olens to normally liquid products without substantial conversionof ethylene, removing said normally liquid productsv thereby leaving aresidual ethylene fraction containing some normally gaseous saturatedhydrocarbons andv from about 5 to 10% of higher molecular Weight oleflnsby weight of the ethylene, passing a stream of `said residual ethylenefraction through an alkylation reaction zone containing a iluidvalkylation catalyst comprising aluminum halide-hydrocarbon 4complexmaintained under alkylating conditions at a temperature in the range of100 to 130 F., passing isobutane to said alkylation reaction zone in theproportion of from 3 to 2O parts isobutane to about 1 part ethylene,effecting reaction between isobutane and ethylene in said alkylationzone in the presence of a small amount of hydrogen halide to formsaturated hydrocarbons of high antiknock value, Withdrawing theresulting alkylated hydrocarbons and 11nreacted normally gaseoussaturated hydrocarbons, and returning said normally gaseous saturatedhydrocarbons to the thermal conversion reaction.

HALSTED ROGERS WARRICK.

